Method of laying cable under ice

ABSTRACT

Cable is laid under ice by a self-propelled, submarine vehicle equipped with a reel of cable for paying out as the vehicle proceeds from a launching hole to a destination hole. A gyrocontrol system is set for the course from the launch hole to the destination hole and guides the vehicle on the first part of its travel, and an acoustic homing system is used to home the vehicle on a transmitter lowered into the water beneath the destination hole to complete the trip. The vehicle is retrieved by passing through large, collapsible loops arranged under the destination hole so that the loops, the threaded cable, and the vehicle can be drawn up through the destination hole.

United States Patent Inventors Appl. No.

Filed Patented Assignee METHOD OF LAYING CABLE UNDER ICE 4 CM 5 Drawing l b.

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flelrlolSeu-el Ides-eons Cited UNITED STATES PATENTS 8/1963 Melton et al .l

6l/69 R,6l/72.3,l

F16] H00 ...6l/69,72.l, 2.3; ll4/l6.42,43

3,507,241 4/1970 Southerland et al l l4/l6 X Primary Examiner- David .I. Williamowsky Assistant Examiner-David H. Corbin Atrorney-Cumpston, Shaw & Stephens ABSTRACT: Cable is laid under ice by a self-propelled. submarine vehicle equipped with a reel of cable for paying out as the vehicle proceeds from a launching hole to a destination hole. A gyrocontrol system is set for the course from the launch hole to the destination hole and guides the vehicle on the first part of its travel, and an acoustic homing system is used to home the vehicle on a transmitter lowered into the water beneath the destination hole to complete the trip. The vehicle is retrieved by passing through large. collapsible loops arranged under the destination hole so that the loops. the threaded cable, and the vehicle can be drawn up through the destination hole.

PATENIEU M1624 l9?! 1400 85;

sum 2 or 2 TQE'MWING 3 SRECEIVING INVENTORS EDWARD C- GODFREY ROBERT A. UBEGA W .L

ATTORNEYS METHOD OF LAYING CABLE UNDER ICE THE INVENTIVE IMPROVEMENT Under-ice, cable-laying vehicles have been previously suggested, but have not been successful. The invention involves the discovery of the necessary characteristics for under-ice, cable-laying vehicles and devising methods and equipment to meet these requirements in an economical and convenient way.

SUMMARY OF THE INVENTION The invention includes a method of laying a cable under ice, an under-ice retrieval system for cable-laying vehicles, and the cable-laying vehicle itself The method involves cutting a hole in the ice at the launching point and the destination point and equipping the vehicle with a supply of cable for laying. A gyrocontrol system in the vehicle is set for the course from the launch point to the destination point, and the vehicle is lowered through the launch hole with the cable secured above the ice. The vehicle's propulsion system is then energized so that the vehicle proceeds on course under control of the gyro system toward the destination point and pays out cable as it goes. A target loop is arranged in the water below the destination hole, and a transmitter is arranged within the target loop. During the course of travel toward the destination hole, the gyrocontrol system is switched off and an acoustic homing system is switched on. The vehicle is sensed as it passes through the loop at the destination hole, and then its propulsion system is stopped and the cable is clamped at the vehicle. The loop is hauled up through the destination hole together with the vehicle and the cable. The target loop is preferably a collapsible device carried on a hoisting line and including a pair of support arms that are resiliently spread apart to hold a flexible loop suspended between the ends of the arms. The vehicle preferably contains electronic control and signalreceiving equipment in a nose section, electric batteries and a reel of cable to be laid in a midsection, and a propulsion motor and propeller, a rudder and a diving plane, and respective control motors in a tail section. The vehicle also includes a clamp arranged for holding the cable from payout whenever the propulsion motor is stopped and for releasing the cable for payout whenever the propulsion motor is energized.

Drawings FIG. I is a partially schematic, elevational view of the inventive method;

FIG. 2 is a partially schematic view ofa cable-laying vehicle for practicing the invention;

FIG. 3 is a partially schematic elevational view of a retrieval device for use in the inventive method;

FIG. 4 is a view of the device of FIG. 3 taken along the line 4-4 thereof; and

FIG. 5 is a partially schematic view of the retrieval of a cable-laying vehicle according to the invention.

Detailed Description:

Under-ice cable-laying is presently required for undersea oil exploration in arctic regions, and it is desirable to lay a cable between under-ice points as much as a mile or so apart. The cold and hostile environment above and below the ice has made such cable-laying previously impractical, but the invention offers a feasible solution.

As generally disclosed in FIG. 1, a self-propelled, submarine, cable-laying vehicle is lowered through hole 11 in ice 12 at a launching point and proceeds toward a target loop 15 lowered through hole 13 in ice 12 at a destination point a considerable distance away from the launch point. Vehicle 10 will be described first, and its launching and retrieval will then be explained.

CABLE-LAYING VEHICLE Vehicle 10 is preferably made in three pieces with detachable couplings 16 and 17 respectively connecting a nose section 18, a midsection 19, and a tail section 20. This allows the vehicle to be taken apart easily above the ice and substitute sections connected together. For example, a replacement midsection 19 can be coupled between previously used nose and tail sections to assemble a new vehicle 10 ready for a new cablelaying trip.

Nose section 18 contains electronic control and signalreceiving equipment for guiding and controlling vehicle 10. A gyrocontrol system 21 controls the travel of vehicle 10 on the initial part of each journey, an acoustic homing transducer 22 arranged in a nose cone 23 forms part of an acoustic homing system for controlling vehicle 10 on the end portion of each journey. A variety of gyrocontrol systems are workable in vehicle 10. and homing transducers and systems other than acoustic can also be used. A switch 25 is arranged to shift the control from the gyrocontrol system to the acoustic homing system, and an acoustic command receiver 26 is also located in the vehicle's electronic system to aid in controlling its journey. Switch 25 can be operated by acoustic command transmitted from above the ice and received by receiver 26, or the acoustic homing transducer 22 can actuate switch 25 when the homing signal received is sufficiently strong for guidance of vehicle 10.

Mid section 19 contains batteries 27 for the main power for vehicle 10 and for powering control motor. A cable reel 28 is also located in midsection 19 for paying out a cable 30 as the vehicle proceeds, and a clamp 29 is arranged for clamping cable 30 against payout.

Tail section 20 contains main propulsion motor 31 powered by battery 27 to turn propeller 32 to drive vehicle 10. Rudder motor 33 in tail section 20 drives rudder 34 to steer vehicle 10, and diving plane motor 35 in tail section 20 positions diving plane 36 to control the depth of travel of vehicle 10. A stern guard 37 is located aft of rudder 34, and cable 30 is guided to the end of stern guard 37 for payout.

Clamp 29 is arranged so that it clamps cable 30 whenever propulsion motor 31 is stopped or deenergized so vehicle 10 can be raised and lowered by cable 30 whenever propulsion motor 31 is stopped. Whenever propulsion motor 31 is energized to turn propeller 32, clamp 29 is released to allow free payout of cable 30. Acoustic command receiver 26 is arranged for controlling the stopping and starting of propulsion motor 31 and the corresponding unclamping and clamping of cable clamp 29. Clamp 29 is preferable an electromagnetic device electrically related to the propulsion system for the preferred actuation.

LAUNCH AND RETRIEVAL SYSTEM Vehicle 10 is assembled at launch hole 11, and gyrocontrol system 21 is set for the course from launch hole 11 to destination hole 13. Target 15 is lowered into the water below destination hole 13, and vehicle 10 is lowered by cable 30 through hole 11. Preferably vehicle 10 is lowered to the desired depth for travel to target 15, and target 15 is set at the same depth. This depth is maintained by a preset depth sensor 46 controlling the diving plane motor 35 and diving plane 36 during the course of travel of vehicle 10. After vehicle 10 reaches such desired depth, an acoustic command delivered to receiver 26 turns on propulsion motor 31 and releases 29 for vehicle 10 to proceed toward target 15 under control of gyrocontrol system 21.

Target 15 is best shown in FIGS. 3-5. It includes a hoisting line 38 lowered through hole 13 by a hoisting sting device 39. Support arms 40 are movably secured to hoist line 38 and are spread apart in respective pairs by springs 41 and are preferably arranged in approximately perpendicular planes as best shown in FIG. 5. Flexible loops 42 extend between the ends of arms 40 as illustrated, to form two large, collapsible, and generally perpendicular loops. A transmitter 43 is arranged preferably near the center of loops 42 to provide an acoustic homing signal for vehicle 10.

When vehicle 10 is sufficiently close to target 15 to home in on the signal from transmitter 43, gyrocontrol system 21 is switched off, and acoustic homing system 24 is switched on either by an acoustic command to receiver 26 or by acoustic homing transducer 22 detecting a sufficiently strong homing signal. Then, with greater precision that is attainable with gyrocontrol system 2!, vehicle 10 homes in on transmitter 43 inside loops 42, and regardless of the angle of its approach, proceeds through one or both loops 42, laying cable 30 in passing.

A 10 device 44 detects the passage of vehicle 10 through target 15, and an acoustic command transmitter 45 signals receiver 26 in vehicle 10 to stop propulsion motor 31 and clamp cable 30 with clamp 29. This lets vehicle 10 settle or float in the water beyond target 15 with cable 30 threaded through at least one of the loops 42. Then target 15 is drawn upward by hoisting device 39, and arms 40 are forced downward against the resilience of springs 41 as the upper ends of arms 40 enter the bottom of hole 13. This brings arms 40 together and allows flexible loops 42 to droop downward as shown in FIG. 5, as target 15 is drawn up through hole 13 in ice 12. This also lifts cable 30 and vehicle 10 up through hole 13 so that cable 30 is then strung from launch H to destination hole 13.

Vehicle 10 can be reassembled with fresh supply of cable and relaunched from hole 13 to a new destination hole at a remote location in ice 12. Meanwhile, cable 30 is used to position hydrophone equipment between hole 11 and hole 13 for generally known under-sea exploration. Vehicle 10 can be made fairly small and lightweight for easy handling in the cold environment and its three-piece construction especially facilitates this. Vehicle 10 does not need any insulated electric wire connection with equipment above ice, and this solves many problems. Retrieval of vehicle 10 with target 15 is fairly simple and does not require a diver The gyrocontrolled initial portion of the journey for vehicle 10 allows a simpler acoustic control and homing system because the gyro can bring vehicle 10 close enough to target l for accurate homing. If the system fails, and vehicle misses target 15, the loss is not excessively expensive, because vehicle Hi can be retrieved by wind ing in cable 30 at launch hole ll. The automatic clamping of cable 30 allows vehicle to be conveniently raised and lowered by the same cable 30 that it will lay under the ice.

Persons wishing to practice the invention should remember that other embodiments and variations can be adapted to par ticular circumstances. Even though one point of view is necessarily chosen in describing and defining the invention, this should not inhibit broader or related embodiments going beyond the semantic orientation of this application but falling within the spirit of the invention. For example, those skilled in the art will appreciate that signals and homing systems is media other than acoustic are possible in the inventive system,

and may variations in the details of vehicle 10 and target 15 are possible within the spirit of the invention.

We claim: l. A method of laying a cable under ice, said method comprising:

a. cutting a hole in said ice at a launching point and at a destination point for said cable; b. equipping a self-propelled, submarine vehicle with a supply of said cable for laying;

a setting a gyrocontrol system in said vehicle for the course from said launching point to said destination point;

. lowering said vehicle through said hole at said launching point with said cable secured above said ice;

. energizing a propulsion system in said vehicle to make said vehicle proceed on said course under control of said gyro system toward said destination point while paying out said cable as said vehicle proceeds; arranging a target loop in the water below said destination hole;

. arran i ng a transmitter within said tar et loop; switc ing said gyrocontrol system 0 and switching on a system for homing said vehicle on said transmitter during the travel of said vehicle;

. sensing the passing of said vehicle through said target loop;

. stopping said vehicle propulsion system and clamping said cable with a clamp on said vehicle after said vehicle has passed through said loop; and

. hauling said loop up through said destination hole to draw said vehicle and said cable up through said destination hole so that said cable is strung from said launch hole to said destination hole.

2v The method of claim 1 including lowering said vehicle at said launching point to a desired depth for travel below said we.

3. The method of claim I wherein said transmitter and said homing system are acoustic.

4. The method of claim 1 including releasing said cable clamp whenever said propulsion system is turned on and applying said cable clamp whenever said propulsion system is stopped so that said vehicle can be raised and lowered by said cable when said propulsion system is stopped, and said vehicle can pay out said cable when said propulsion system is running. 

1. A method of laying a cable under ice, said method comprising: a. cutting a hole in said ice at a launching point and at a destination point for said cable; b. equipping a self-propelled, submarine vehicle with a supply of said cable for laying; c. setting a gyrocontrol system in said vehicle for the course from said launching point to said destination point; d. lowering said vehicle through said hole at said launching point with said cable secured above said ice; e. energizing a propulsion system in said vehicle to make said vehicle proceed on said course under control of said gyro system toward said destination point while paying out said cable as said vehicle proceeds; f. arranging a target loop in the water below said destination hole; g. arranging a transmitter within said target loop; h. switching said gyrocontrol system off and switching on a system for homing said vehicle on said transmitter during the travel of said vehicle; i. sensing the passing of said vehicle through said target loop; j. stopping said vehicle propulsion system and clamping said cable with a clamp on said vehicle after said vehicle has passed through said loop; and k. hauling said loop up through said destination hole to draw said vehicle and said cable up through said destination hole so that said cable is strung from said launch hole to said destination hole.
 2. The method of claim 1 including lowering said vehicle at said launching point to a desired depth for travel below said ice.
 3. The method of claim 1 wherein said transmitter and said homing system are acoustic.
 4. The method of claim 1 including releasing said cable clamp whenever said propulsion system is turned on and applying said cable clamp whenever said propulsion system is stopped so that said vehicle can be raised and lowered by said cable when said propulsion system is stopped, and said vehicle can pay out said cable when said propulsion system is running. 